Disposable absorbent article comprising expandable fibers and being capable of self-shaping in use

ABSTRACT

A substantially flat disposable absorbent article for wearing adjacent a body discharge area having a longitudinal centerline, and a lateral centerline orthogonal thereto, and defining longitudinal and lateral directions respectively. The disposable absorbent article includes a liquid pervious top sheet, a back sheet joined to the top sheet, and an absorbent core intermediate the back sheet and the top sheet. The absorbent core includes a layer of compressed, cellulose based, linear fibers for expanding the article into a tridimensional structure while being worn by a user. The layer of compressed, cellulose based, linear fibers is activated by body fluids.

FIELD OF THE INVENTION

The present invention relates to disposable absorbent articles.Disposable absorbent articles are considered to be absorbent devicesdesigned to be worn externally of the body by a user and to receivefluids discharged from the body. In particular the present inventionrelates to substantially flat disposable absorbent sanitary napkins,catamenials, incontinence inserts, pantiliners and diapers comprising alayer of compressed fibres for expanding the article into atridimensional structure while being worn by a user. The layer ofcompressed fibres is activated by body fluids and provides the articlewith a self-shaping capability during the use.

BACKGROUND OF THE INVENTION

In their basic form, disposable absorbent articles comprise an absorbentcore interposed between a pervious body-contacting element(alternatively referred to as a topsheet or an overwrap) and animpervious protective barrier (alternatively referred to as abacksheet). The absorbent element is, of course, intended to receive andcontain the fluids discharged from the body. The body-contacting elementis intended to provide comfortable and dry-feeling contact with bodysurfaces while allowing free passage of fluids therethrough into theabsorbent element. The protective barrier is intended to prevent thefluids which are expelled or which escape from the absorbent elementfrom soiling the user's garments.

In addition to the three functional elements mentioned above, disposableabsorbent articles are generally provided with means for supporting thedevice adjacent the user's crotch area, even as the user moves, where itcan most effectively perform its intended function. Typically, absorbentarticles as sanitary napkins are provided with an adhesive attachmentmeans for securing the device to the inner crotch area of the user'sundergarments.

Improved fluid interception can occur if the absorbent article is inclose contact with the body of the wearer.

While previously known absorbent articles perform their intendedfunction, each conventional design can be further improved in one ormore of absorbency of body fluids, protection of the user's garmentsfrom soiling, and/or physical comfort to the user.

With respect to disposable sanitary napkins several attempts have beenmade in the art to improve body contact with the wearer, and henceabsorb fluids upon discharge and thereby minimize soiling by providing asanitary napkin having an anatomically shaped configuration,particularly including those that are raised upwardly or humped in theirmedial portions so as to be near or in contact with the pudendal regionwhen worn.

On female users these sanitary napkins attempt to contact and absorbmenses immediately as it leaves the vestibule.

Some articles have been also described in which an anatomically shapedconfiguration is provided during the wearing time, with the advantage ofa better fit to the anatomy.

According to U.S. Pat. No. 3,512,530 a sanitary napkin is described inwhich a compressed regenerated cellulose sponge layer is combined with alarger fibrous cellulose layer to form a multiple ply absorbent core.The compressed regenerated cellulose sponge layer is positioned over thefibrous layer, and it is typically centered about it; it is intended asthe primary absorbent element of the sanitary napkin, while the fibrouslayer acts as a secondary or back up absorber.

The sanitary napkin may be therefore very thin prior to use, as comparedto other sanitary products having the same absorbent capacity.

Although the compressed regenerated cellulose sponge layer is capable ofexpanding in Z-direction upon fluid absorption, the structure describedis not particularly suitable to provide an effective body contact withthe wearer's anatomy and might cause discomfort to the user due to thecharacteristics of the compressed regenerated cellulose sponge material,particularly when it is dry.

EP Patent 293 208 B1 describes the use of multiple layers of compressedregenerated cellulose sponge sheets in a sanitary napkin as the soleabsorbent material instead of the usual cellulose pulp absorbent core inorder to obtain an absorbent article of improved strength and shaperetainability in wet conditions, as compared to traditional absorbentarticles with fluff cores that tend to be broken or to form lumps inuse.

The sheets are provided with slits in order to enhance theirflexibility, with a better comfort for the user, and to increase thefluid absorbing area.

The sanitary napkin described in the EP patent 293 208 B1 has astructure that is not specifically intended to provide a self shapingcapability during the use taking advantage of the swelling of theabsorbent material, but rather a better strength when wetted thanarticles using conventional, fluff-based absorbent cores, and a betterflexibility and absorbency rate as compared to articles using the samecompressed regenerated cellulose sponge material.

U.S. Pat. No. 3,736,931 discloses a sanitary napkin having an outernon-compressed layer of fluid absorbent material and an inner core ofhighly compressed fluid absorbent material which is at least partiallyenclosed therein. The napkin preferably is V-shaped in cross section andis arch-shaped in its longitudinal direction by die compression. Whenthe napkin is worn the fluid directs first into the inner compressedlayer so as to cause it to swell and to expand the outer non-compressedlayer in all directions, thereby adjusting itself to each wearer.

The sanitary napkin expands upon fluid absorption and may adjust itselfto the user's anatomy, but since it is not flat prior to use it may becumbersome to package and to handle; moreover, the expansion takes placemainly in the lateral direction, thus achieving an effective sealagainst the inner side of the thighs and at both sides of the vaginalorifice; therefore the structure is neither capable of forming a convexupward configuration nor does it bring the absorbent element in directcontact with the point of release of the fluid.

Therefore there is still the need for an absorbent article capable ofproviding an anatomically shaped configuration for a closer body contactwhich is achieved during the use upon activation by absorbed bodyfluids, while it is comfortable for the wearer and easy to produce andto package.

SUMMARY OF THE INVENTION

The present invention relates to disposable absorbent articles forwearing adjacent a body discharge area which are substantially flatprior to use. The substantially flat disposable absorbent article has alongitudinal centreline and a lateral centreline orthogonal thereto thatdefine longitudinal and lateral directions respectively and aZ-direction which is orthogonal to both of them. The disposableabsorbent article comprises a liquid pervious topsheet, a backsheet,preferably liquid impervious, joined to said topsheet, and an absorbentcore intermediate the topsheet and the backsheet. The term“substantially flat”, as used herein, refers to articles which havetheir main extension in one plane in contrast to being shaped. Theabsorbent core comprises a layer of compressed, regenerated cellulose,linear fibres capable of expanding the article into a tridimensionalstructure while being worn by a user and having a dry density of from0.1 g/cc to 0.4 g/cc, wherein the layer of compressed fibres isactivated by body fluids and has a thickness of between 2 mm to 7 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the present invention, it is believed that thepresent invention will be better understood from the followingdescription in conjunction with the following drawings:

FIG. 1 is a top plan view, with portions cut-away of one embodiment of asanitary napkin according to the present invention;

FIG. 2 is a cross-sectional view of the sanitary napkin shown in FIG. 1as taken along a section line corresponding to the transverse centrelineA—A;

FIG. 3 is a cross-sectional view similar to that of FIG. 2, showing thesanitary napkin expanded into a tridimensional structure afteractivation during wear;

FIG. 4 is a cross-sectional view of another embodiment of a sanitarynapkin according to the present invention;

FIG. 5 is a cross-sectional view similar to that of FIG. 2, showing thesanitary napkin expanded into a tridimensional structure afteractivation during wear.

DETAILED DESCRIPTION OF THE INVENTION

This invention relates to a disposable absorbent article which exhibitsabsorbency for bodily fluids, the protection of the user's garments fromsoiling, improved physical comfort to the user, and which is easy toproduce and to package. The disposable absorbent article is describedbelow by is reference to a sanitary napkin or catamenial. The term“sanitary napkin”, as used herein, refers to an article which is worn byfemales adjacent to the pudendal region and which is intended to absorband contain the various fluids which are discharged from the body (e.g.,vaginal discharges, menses, and/or urine) and which is intended to bediscarded after a single use. The disposable absorbent article issubstantially flat prior to use.

The term “substantially flat”, as used herein, refers to articles thathave their main extension in one plane in contrast to being shaped. In apreferred embodiment a substantially flat article will have an absorbentcore of constant thickness or, at least, will have an absorbent corethat is not shaped in a direction which is orthogonal to the absorbentcore itself. This does not exclude a general curvature of the absorbentcore. It will be apparent to the man skilled in the art to which extentproducts can deviate from absolute flat shape and still benefit from theduring the use shaping according to the present invention.

Sanitary napkins with longitudinal side cuffs, which may be optionallyelasticated, and sanitary napkins with a moderate curvature aretherefore within the scope of the present invention, provided that theirabsorbent core is not shaped prior to use in a direction that isorthogonal to the absorbent core itself.

The term “use”, as used herein, refers to the period of time that startswhen the absorbent article is actually put in contact with the anatomyof the user.

The terms “joined” or “affixed”, as used herein, encompassesconfigurations whereby a first member is directly connected to a secondmember and configurations whereby a first member is indirectly connectedto a second member by connecting the first member to intermediatemembers which in turn are connected to the second member.

Interlabial devices which reside partially within and partially externalof the wearer's vestibule are also within the scope of this invention.As used herein, the term “pudendal” refers to the externally visiblefemale genitalia and is limited to the labia majora, the labia minora,the clitoris, and the vestibule.

In FIGS. 1 and 2, one preferred embodiment of a sanitary napkin 20 ofthe present invention is shown. FIG. 1 is a plan view of the sanitarynapkin 20 of the present invention in its flat-out state prior to usewith portions of the structure being cut-away to more clearly show theconstruction of the sanitary napkin 20 and with the portion of thesanitary napkin 20 which faces or contacts the wearer oriented towardsthe viewer. As shown in FIGS. 1 and 2, the sanitary napkin 20 preferablycomprises a liquid pervious topsheet 24, a liquid impervious backsheet26 joined to the topsheet 24, and an absorbent core 28 intermediate thetopsheet 24 and the backsheet 26 comprising a layer of compressed fibres46 for expanding the sanitary napkin into a tridimensional structurewhile being worn by a user.

The sanitary napkin 20 has two surfaces, a body contacting or facingsurface, and a garment facing or contacting surface. The absorbent core28 has corresponding body facing and garment facing surfaces. Thesanitary napkin 20 has two centrelines, a longitudinal centreline O—Oand a transverse centreline A—A orthogonal thereto. The term“longitudinal”, as used herein, refers to a line, axis or direction inthe plane of the sanitary napkin 20 that is generally aligned with(e.g., approximately parallel to) a vertical plane which bisects astanding wearer into left and right body halves when the sanitary napkin20 is worn. The terms “transverse” or “lateral”, as used herein, areinterchangeable, and refer to a line, axis, or direction which lieswithin the plane of the sanitary napkin 20 and is generallyperpendicular to the longitudinal direction. The Z-direction isorthogonal to both the longitudinal and lateral directions of thesanitary napkin 20 and extends outwardly from the plane of the sanitarynapkin 20, which is defined by the longitudinal centreline 0—0 and thelateral centreline A—A. The term “longitudinally oriented” refers to adirection ±45 degrees of the longitudinal direction in the plane of thesanitary napkin 20; the term “laterally oriented” refers similarly toany other direction in the plane of the sanitary napkin 20.

The long edges of the sanitary napkin 20, which are aligned with thelongitudinal centreline O—O, are the longitudinal side margins of thesanitary napkin 20. The ends of the sanitary napkin 20 joining thelongitudinal side margins are the transverse ends of the sanitary napkin20. Collectively the longitudinal side margins and transverse ends ofthe sanitary napkin 20 define its periphery. Similarly, the absorbentcore 28 of the sanitary napkin 20 has a periphery defined byalternatively disposed longitudinal side margins and transverse ends.

Tridimensional structures of the sanitary napkin 20 are those in whichthe sanitary napkin structure is caused to expand, at least partially,in the Z-direction, in order to more closely conform to the user'sanatomy. Said expansion preferably takes place in a direction that goesfrom the garment facing surface towards the body facing surface of thesanitary napkin 20. Particularly preferred are tridimensional structureswith a convex upward configuration that are inclusive of, but notlimited to, inverted U-shapes or inverted V-shapes. With theseconfigurations the cross-sectional contour of the central portion of thesanitary napkin more closely matches the labia of the typical wearer.

The topsheet 24 is compliant, soft feeling, and non-irritating to thewearer's skin. Further, the topsheet 24 is liquid pervious, permittingliquid to readily penetrate through its thickness. A suitable topsheet24 may be manufactured from a wide range of materials such as woven andnonwoven materials; polymeric materials such as apertured formedthermoplastic films, apertured plastic films, and hydroformedthermoplastic films; porous foams; reticulated foams; reticulatedthermoplastic films; and thermoplastic scrims. Suitable woven andnonwoven materials can be comprised of natural fibres (e.g., wood orcotton fibers), synthetic fibres (e.g., polymeric fibres such aspolyester, polypropylene, or polyethylene fibres); or from a combinationof natural and synthetic fibres.

A preferred topsheet comprises an apertured formed film. Aperturedformed films are preferred for the topsheet because they are pervious tobody fluids and yet non-absorbent and have a reduced tendency to allowliquids to pass back through and rewet the wearer's skin. Thus, thesurface of the formed film which is in contact with the body remainsdry, thereby reducing body soiling and creating a more comfortable feelfor the wearer.

Suitable formed films are described in U.S. Pat. No. 3,929,135, issuedto Thompson on Dec. 30, 1975; U.S. Pat. No. 4,324,246, issued toMullane, et al. on Apr. 13, 1982; U.S. Pat. No. 4,342,314, issued toRadel, et al. on Aug. 3, 1982; U.S. Pat. No. 4,463,045, issued to Ahr,et al. on Jul. 31, 1984; and U.S. Pat. No. 5,006,394, issued to Baird onApr. 9, 1991. A preferred topsheet for the absorbent article of thepresent invention is a formed film described in one or more of the abovepatents and marketed on sanitary napkins by The Procter & Gamble Companyof Cincinnati, Ohio as DRI-WEAVE.

In a preferred embodiment of the present invention, the body or exposedsurface of the formed film topsheet is hydrophilic so as to help liquidtransfer through the topsheet faster than if the body surface were nothydrophilic so as to diminish the likelihood that menstrual fluid willflow off the topsheet rather than flowing into and being absorbed by theabsorbent core.

The topsheet of the present invention must be capable of expanding asthe sanitary napkin 20 expands in a tridimensional structure uponabsorption of body fluids. This may be achieved when the topsheet ismade of a material that is intrinsically extensible under the forcesexerted by the expanding layer of compressed fibres 46. In a preferredembodiment illustrated in FIGS. 1 and 2 the topsheet 24 is provided withtwo pleats or folds 52 symmetrically positioned at both sides of thelongitudinal centreline O—O and substantially parallel to it. As shownin FIG. 2 the topsheet 24 in each pleat or fold 52 is folded twice onitself toward the longitudinal side margins of the sanitary napkin 20. Asingle pleat or fold or, alternatively, more than two folds may be alsocomprised in the topsheet 24 without departing from the scope of thepresent invention; the pleats or folds may be generally longitudinallyor laterally oriented.

In a preferred embodiment illustrated in FIGS. 1 to 3 absorbent core 28is entirely constituted by the layer of compressed fibres 46.

Alternatively, the absorbent core 28 can also comprise a further,substantially non expanding absorbent element.

The further, substantially non expanding absorbent element of theabsorbent core 28 may be any absorbent means which is generallycompressible, resilient, non-irritating to the wearer's skin and capableof absorbing and containing body fluids. The absorbent core 28 may bemanufactured from a wide variety of liquid absorbent materials commonlyused in disposable sanitary napkins, and other disposable absorbentarticles. Examples of suitable absorbent materials include comminutedwood pulp (which is generally referred to as airfeft), creped cellulosewadding, modified cross-linked cellulose fibres (such as those describedin U.S. Pat. No. 5,217,445 issued to Young, et al. on Jun. 8, 1993),capillary channel fibres (that is, fibres having intra-fibre capillarychannels such as those described in U.S. Pat. No. 5,200,248 issued toThompson, et al. on Apr. 6, 1993), absorbent foams (such as thosedescribed in U.S. Pat. No. 5,260,345, issued to DesMarais, et al. onNov. 9, 1993 and U.S. Pat. No. 5,268,244 issued to DesMarais, et al. onDec. 7, 1993), thermally bonded airlaid materials (such as thosematerial described in U.S. patent application Ser. No. 08/141,156,entitled “Catamenial Absorbent Structures Having Thermally Bonded LayersFor Improved Handling of Menstrual Fluids and Their Use In CatamenialPads Having Improved Fit and Comfort” filed in the name of Richards, etal. on Oct. 21, 1993 (P&G Case 5051)), absorbent sponges, syntheticstaple fibres, polymeric fibres, hydrogel-forming polymer gellingagents, peat moss, or any equivalent materials or combinations ofmaterials. Suitable absorbent cores comprising foams are described inEuropean Applications 0 598 833, 0 598 823 and 0 598 834.

The total absorbent capacity of the absorbent core 28 should becompatible with the intended body fluid loading for the sanitary napkin20. Further, the absorbent capacity may be varied to accommodate wearersranging in the expected amount of body fluid volume. For instance, adifferent absorbent capacity may be utilized for sanitary napkinsintended for day time use as compared with those intended for night timeuse, or for sanitary napkins intended for use by teenage females ascompared with those intended by more mature women.

According to a preferred embodiment of the present invention theabsorbent core 28 of the sanitary napkin 20 is entirely constituted by alayer of compressed fibres 46 that performs the absorption of bodyfluids and is also intended for expanding the sanitary napkin 20 intothe desired tridimensional structure while the sanitary napkin 20 isbeing worn. In the embodiment illustrated in FIGS. 1 to 3 the expansionand the final shaping of the sanitary napkin 20 into the tridimensionalstructure is provided by the swelling, substantially in Z-direction, ofthe material that constitutes the layer of compressed fibres 46 and thatis activated during wear by the absorption of body fluids.

The fibres used for the compressed layer 46 of the present inventionmainly comprise artificial, cellulose derived hydrophilic fibres. Thefibres are substantially linear, that is, they are not curled, eventhough they may be slightly crimped in order to improve theirprocessability. The fibres have a length of 10 to 70 mm, preferably of40 to 50 mm, and a diameter of 1 to 20 dtex, preferably from 2 to 10dtex. The fibres are air laid to form a layer of the desired basisweight, and then compressed to get a compressed layer having a thicknesscomprised, between 2 and 7 mm and a density that may range from 0.1 g/ccto 0.4 g/cc.

Materials selected for use as the layer of compressed fibres 46 arepreferably compliant, comfortable and resilient in their dry, compressedstate to enhance body fit and comfort of the sanitary napkin 20.

In a preferred embodiment of the present invention regenerated cellulosehydrophilic fibres prepared according to any well known method, e.g. theprocessing of pre-hydrolyzed sulphate chemical wood pulp to rayon by theviscose process, may be used for the layer 46.

Regenerated cellulose hydrophilic fibres with particular cross-sectionsthat improve the pick up and delivery of fluids may also be used, e.g.fibres with a trilobal section or fibres with capillary channels formedtherein, preferably on their exterior surfaces.

The density of the layer of compressed fibres 46 may be uniformthroughout its entire surface, or may preferably vary either inlongitudinal or in lateral direction, or in both. A layer of compressedfibres 46 having non uniform densities may be easily made e.g. bycompressing to a uniform thickness a layer of fibres having zones withdifferent basis weights, and therefore different thicknesses beforecompression.

In a preferred embodiment illustrated in FIGS. 1 to 3 the layer ofcompressed fibres 46 has a density that has its highest value at itscentre and gradually decreases to a common minimum value towards boththe longitudinal side margins and the transverse ends of the layer 46,so establishing a density gradient from the periphery to the centre ofthe layer of compressed fibres 46.

The fibres of the compressed layer 46 are completely unbonded or,alternatively, may be bonded with a binder prior to compression.Suitable binders are those that are water soluble; they may be used insuch an amount that does not impair the subsequent swelling of the layerupon absorption of body fluids, preferably an amount not greater than20% in weight.

Particles of absorbent gelling material may also be included within thelayer of compressed fibres 46, preferably when it constitutes theabsorbent core 28 of the sanitary napkin 20.

Natural fibres as cellulose or cotton fibres or synthetic fibres of thesame length as the regenerated cellulose fibres, such as polyethylene,polypropylene or polyester fibres, may also be used in combination withthe regenerated cellulose fibres to form the compressed layer 46, in anamount up to 50 weight %.

A layer of compressed regenerated cellulose fibres is capable ofabsorbing liquid very fast, with a rapid swelling in the direction ofthe compression; the swelling ratio is 2 to 10 times the dry thicknessof the sheet.

In a preferred embodiment of the present invention, which is illustratedin FIGS. 1 and 2, a layer 46 of compressed regenerated cellulose fibreswith a dry density of 0.125 g/cmc at its periphery which increases up to0.2 g/cmc at its centre and a uniform thickness of 4 mm constitutes theabsorbent core of the sanitary napkin 20. The layer 46 is 207 mm longand 64 mm wide. Suitable fibres for the layer 46 are regeneratedcellulose linear fibres 40 mm long and with a thickness of 1.7 dtex, asthose produced by Lenzing AG.

The layer of compressed regenerated cellulose fibres 46 is capable ofabsorbing body fluids quickly with a large increase in its volume,generally from about 2 to 10 times, and usually from 3 to 7 times itsvolume at the time of the compression; the volume increase depends onthe density of the compressed layer: it is higher as the density of thelayer of compressed fibres increases. The volume increase substantiallycorresponds to a swelling in the direction of the compression, that isin the Z-direction in the sanitary napkin 20.

The sanitary napkin 20 is produced and packaged as a conventional flatproduct, as illustrated in FIGS. 1 and 2. After the sanitary napkin 20has been worn, as soon as the absorbed body fluids come in contact withthe material of the layer of compressed fibres 46, this will begin toswell in Z-direction increasing its thickness, as can be seen in FIG. 3.Due to the density gradient that is preferably comprised in the layer ofcompressed fibres 46 the total swelling of the layer upon absorption ofbody fluids will not be uniform throughout its width and length, butwill realize a profile that substantially follows the profile of thedensity gradient itself, that is, as illustrated in FIG. 3 with respectto the transverse dimension, the swelling will be higher at the centreof the layer 46, gradually decreasing towards the two longitudinal sidemargins. A similar configuration, not illustrated, will be achieved inlongitudinal direction.

The topsheet 24 follows the swelling of the layer of compressed fibres46 by straightening out the pleats or folds 52, therefore increasing itswidth without restraining the swelling.

After the absorption of body fluids and the subsequent swelling, thematerial of the layer of compressed fibres 46 is soft, compliant,conformable and resilient. It is compressible such that it will deformunder the relatively small forces that are experienced during normaluse. In addition to be compressible, the material of the layer ofcompressed fibres 46 is after swelling flexible and conformable suchthat it is able to provide improved fit through the topsheet 24 into andaround the wearer's labia and perineum when the tridimensional structureis formed during the wearing time. The ability to follow the topographyof the anatomy will provide intimate contact with the exposed genitaliaof the female user. This helps provide better fluid transfer from theuser into the layer of compressed fibres 46. While these characteristicsof the layer of compressed fibres 46 allow for improved fit, they alsocause the product to be both soft and comfortable for the wearer.

The swelling upon liquid absorption of the compressed fibres spongematerial that forms the layer 46 creates a void volume that does notcollapse in wet conditions and therefore enables the material to rapidlyacquire further releases.

The swelling of the material forming the layer of compressed fibres 46takes place only upon activation by the absorbed fluid, that is onlyduring the use of the sanitary napkin 20 and in close contact with theuser's anatomy; the formation of the tridimensional structure cantherefore achieve a much better fit with the anatomy of the user.Moreover, the swelling of the layer of compressed fibres 46 may startwhere it is actually reached by the fluid first; the formation of thetridimensional structure may also fit, therefore, the different possibleways in which the body fluids may be released by various users.

The expanding topsheet 24 also provides a comfortable contact with theuser's anatomy, without restraining the expansion of the sanitary napkininto the desired tridimensional structure upon activation by bodyfluids.

The sanitary napkin of the present invention is flat prior to use, andmay be therefore manufactured and packaged more easily than aconventional elasticated or preformed article. Since the tridimensionalstructure is formed only during the use, the sanitary napkin of thepresent invention is also easier to wear.

In an alternative embodiment of the present invention, the sanitarynapkin 20 may have two flaps (not shown), each of which are adjacent toand extend laterally from the side edge of the absorbent core. The flapsare configured to drape over the edges of the wearer's panties in thecrotch region so that the flaps are disposed between the edges of thewearer's panties and the wearer's thighs. The flaps serve at least twopurposes. First, the flaps help serve to prevent soiling of the wearer'sbody and panties by menstrual fluid, preferably by forming a double wallbarrier along the edges of the panty. Second, the flaps are preferablyprovided with attachment means on their garment facing surface so thatthe flaps can be folded back under the panty and attached to the garmentfacing side of the panty. In this way, the flaps serve to keep thesanitary napkin properly positioned in the panty.

The flaps may be constructed of various materials including materialsused for the topsheet 24, backsheet 26, combinations thereof, and may bea laminate having tissue in the centre. Further, the flaps may be aseparate element attached to the main body of the sanitary napkin 20 orcan comprise extensions of the topsheet 24 and/or backsheet 26. It isrecommended, however, that the flaps have a liquid impervious backsheetto prevent body fluids which reach the flaps from soiling the edges ofthe wearer's panties.

Preferred flaps that are suitable or adaptable to the sanitary napkin 20of the present invention are disclosed in U.S. Pat. No. 4,687,478 issuedto Van Tilburg on Aug. 18, 1987; U.S. Pat. No. 4,589,876 issued to VanTilburg on May 20, 1986; and U.S. Pat No. 4,608,047 issued to Mattinglyon Aug. 26, 1986.

Optionally, the sanitary napkin 20 may comprise components thatnaturally wrap the sides of a wearer's panties. Sanitary napkins havingcomponents that naturally wrap the sides of a wearer's panties suitablefor use with the sanitary napkin 20 of the present invention aredisclosed in U.S. patent application Ser. No. 08/096,121 entitled“Absorbent Article having Panty Covering Components that Naturally Wrapthe Sides of Panties”, filed Jul. 22, 1993, in the names of Lavash, etal and U.S. patent application Ser. No. 08/277,733 entitled “AbsorbentArticles Having Undergarment Covering Components with Zones ofExtensibility”, filed Jul. 20, 1994, in the names of Weinberger, et al.

In an alternative embodiment illustrated in FIGS. 4 and 5 a sanitarynapkin 20 similar to that illustrated in FIGS. 1 and 2 has an absorbentcore 28 that comprises a further, substantially non-expanding absorbentelement positioned between the layer of compressed fibres 46 and thebacksheet 26. In the embodiment illustrated in FIGS. 4 and 5, thisabsorbent element is comprised of an absorbent layer 30 made of athermally bonded airlaid material longitudinally folded twice on itselfand comprising particles of absorbent gelling material therebetween,which are not shown for clarity.

The layer of compressed fibres 46 preferably forms at least part of thebody facing surface of the absorbent core 28.

In the embodiment illustrated in FIGS. 4 and 5 the layer of compressedfibres 46 is positioned over the substantially non-expanding absorbentlayer 30, in face to face relationship with it; it has the same lengthand width as the absorbent layer 30; alternatively, it can be smallerthan the absorbent layer 30, either in width, or in length, or both,being preferably centered about the longitudinal and transversecentrelines O—O and A—A.

In the alternate embodiment shown in FIGS. 4 and 5 the total absorbentcapacity of the sanitary napkin 20 is substantially provided for by thecombination of the layer of compressed fibres 46 with the substantiallynon-expanding absorbent layer 30; the layer of compressed fibres 46 maybe therefore suitably dimensioned, in length, width, thickness anddensities, to get, in combination with the substantially non-expandingabsorbent layer 30, the desired absorbent capacity for the sanitarynapkin 20.

As illustrated in FIG. 4, the pleats or folds 52 of the topsheet 24 arepositioned at both sides of the longitudinal centreline O—O andsubstantially parallel to it, but, differently from what is shown inFIG. 2, in each pleat or fold 52 the topsheet 24 is folded twice onitself toward the longitudinal centreline O—O of the sanitary napkin 20.During the swelling of the layer of compressed fibres 46 upon fluidabsorption the straightening out of the pleats or folds 52 forms a sortof longitudinally oriented side cuffs 47 that provide a better sealagainst side leakage, as illustrated in FIG. 5; the side cuffs 47 maystill be present when the swelling of the layer of compressed fibres 46is completed if the overall width of the topsheet 24 is slightly higherthan that which would be necessary to follow the complete swelling ofthe compressed regenerated cellulose sponge sheet 46.

In a further alternative embodiment, which is not illustrated, thesanitary napkin 20 may also comprise an acquisition layer or secondarytopsheet positioned e.g. between the topsheet 24 and the absorbent core28. The acquisition layer may serve several functions includingimproving wicking of body fluids over and into the underlying layers. Byimproving the wicking of body fluids, the acquisition layer provides amore even distribution of the body fluids throughout the underlyinglayers.

The acquisition layer can be positioned in the sanitary napkin 20 in anysuitable position, as it is apparent to the man skilled in the art, butin any case it must be free to follow the expansion of the layer ofcompressed fibres 46 upon absorption of liquid, without restraining itsswelling.

The acquisition layer preferably comprises materials that are capable ofacquiring liquid very fast, and subsequently release it to underlyinglayers with substantially no retention capacity; suitable materialsinclude nonwoven or woven webs of synthetic fibres including polyester,polypropylene, or polyethylene; natural fibres including cotton orcellulose; blends of such fibres; or any equivalent materials orcombinations of materials. Examples of sanitary napkins having anacquisition layer and a topsheet are more fully described in U.S. Pat.No. 4,950,264 issued to Osborn and U.S. patent application Ser. No.07/810,774, “Absorbent Article Having Fused Layers”, filed Dec. 17, 1991in the names of Cree, et al.

1. A sanitary napkin to be worn by a female user adjacent to herpudendal region, the sanitary napkin having a longitudinal centerlineand a lateral centerline orthogonal thereto and defining longitudinaland lateral directions, respectively, the sanitary napkin further havinga Z-direction which is orthogonal to both the longitudinal and thelateral directions, the sanitary napkin further comprising a liquidpervious topsheet, a backsheet joined to the topsheet, and an absorbentcore intermediate the topsheet and the backsheet, the absorbent corecomprising a body faceable surface, the sanitary napkin beingsubstantially flat prior to use, wherein the absorbent core comprises alayer of compressed, regenerated cellulose, linear fibers capable ofexpanding the sanitary napkin into a tridimensional structure whilebeing worn by the user and having a dry density of from 0.1 g/cc to 0.4g/cc, the expanding layer of compressed, cellulose, linear fibers havinga thickness of between 2 mm to 7 mm, and the expanding layer ofcompressed, cellulose, linear fibers being activateable by body fluidsfrom the female user.
 2. The sanitary napkin of claim 1 wherein thelayer of compressed, cellulose, linear fibers provides the sanitarynapkin with a substantially convex upward configuration.
 3. The sanitarynapkin of claim 1 wherein the topsheet is capable of expanding as thesanitary napkin expands upon activation by body fluids.
 4. The sanitarynapkin of claim 3 wherein the topsheet has at least a pleat or fold. 5.The sanitary napkin of claim 1 wherein the layer of compressed,cellulose, linear fibers upon activation by body fluids expandssubstantially in the Z-direction to provide the tridimensionalstructure.
 6. The sanitary napkin of claim 1 wherein the layer ofcompressed, cellulose, linear fibers forms at least part of the bodyfaceable surface of said absorbent core.
 7. The sanitary napkin of claim1 wherein the regenerated cellulose fibers have a length of 10 mm to 70mm and a diameter of from 1 dtex to 20 dtex.